Methods and apparatus for vehicle suspension having multiple gas volumes

ABSTRACT

A method and apparatus for a vehicle suspension system gas spring. In one embodiment, a vehicle suspension system gas spring includes a compressible main gas chamber and an additional volume combinable with the main chamber to change a gas spring rate of the system. In one embodiment, a low friction piston seal is created by a flexible seal member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and is a continuation of theco-pending patent application, U.S. patent application Ser. No.13/005,474, filed on Jan. 12, 2011, entitled “METHODS AND APPARATUS FORVEHICLE SUSPENSION HAVING MULTIPLE GAS VOLUMES”, by Mario Galasso etal., Attorney Docket Number FOX/F0042USP1, and assigned to the assigneeof the present invention, the disclosure of which is hereby incorporatedherein by reference in its entirety.

The U.S patent application Ser. No. 13/005,474 is a continuation-in-partapplication of and claims the benefit of U.S. patent application Ser.No. 12/717,867, filed on Mar. 4, 2010, now abandoned, entitled “METHODSAND APPARATUS FOR COMBINED VARIABLE DAMPING AND VARIABLE SPRING RATESUSPENSION” by Dennis K. Wootten et al., with Attorney Docket No.FOXF/0034USP1, and assigned to the assignee of the present application,which is incorporated herein, in its entirety, by reference.

The U.S. patent application Ser. No. 12/717,867 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/157,541, filed onMar. 4, 2009, entitled “METHODS AND APPARATUS FOR COMBINED VARIABLEDAMPING AND VARIABLE SPRING RATE SUSPENSION” by Dennis K. Wootten etal., with Attorney Docket No. FOXF/0034L, which is incorporated herein,in its entirety, by reference.

The U.S patent application Ser. No. 12/717,867 is a continuation-in-partapplication of and claims the benefit of U.S. patent application Ser.No. 12/509,258, filed on Jul. 24, 2009, and is now issued U.S. Pat. No.8,869,959, entitled “VEHICLE SUSPENSION DAMPER” by Joshua BenjaminYablon et al., with Attorney Docket No. FOX-0027L-US, and assigned tothe assignee of the present application, which is incorporated herein,in its entirety, by reference.

The U.S. patent application Ser. No. 12/509,258 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/227,775, filed onJul. 22, 2009, entitled “VEHICLE SUSPENSION DAMPER” by Joshua BenjaminYablon et al., with Attorney Docket No. FOX-0027L-PRO, which isincorporated herein, in its entirety, by reference.

The U.S patent application Ser. No. 12/717,867 is a continuation-in-partapplication of and claims the benefit of U.S. patent application Ser.No. 12/407,610, filed on Mar. 19, 2009, and is now issued U.S. Pat. No.8,894,050, entitled “METHODS AND APPARATUS FOR SUSPENDING VEHICLES” byDennis K. Wootten et al., with Attorney Docket No. FOXF/0022, andassigned to the assignee of the present application, which isincorporated herein, in its entirety, by reference.

The U.S. patent application Ser. No. 12/407,610 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/038,015, filed onMar. 19, 2008, entitled “METHODS AND APPARATUS FOR SUSPENSION VEHICLESUSING MULTIPLE FLUID VOLUMES” by Dennis K. Wootten et al., with AttorneyDocket No. FOXF/0022L, which is incorporated herein, in its entirety, byreference.

The U.S. patent application Ser. No. 12/407,610 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/157,541, filed onMar. 4, 2009, entitled “METHODS AND APPARATUS FOR COMBINED VARIABLEDAMPING AND VARIABLE SPRING RATE SUSPENSION” by Dennis K. Wootten etal., with Attorney Docket No. FOXF/0034L, which is incorporated herein,in its entirety, by reference.

The U.S. patent application Ser. No. 13/005,474 is acontinuation-in-part application of and claims the benefit of U.S.patent application Ser. No. 12/407,610, filed on Mar. 19, 2009, and isnow issued U.S. Pat. No. 8,894,050, entitled “METHODS AND APPARATUS FORSUSPENDING VEHICLES” by Dennis K. Wootten et al., with Attorney DocketNo. FOXF/0022, and assigned to the assignee of the present application,which is incorporated herein, in its entirety, by reference.

The U.S. patent application Ser. No. 12/407,610 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/038,015, filed onMar. 19, 2008, entitled “METHODS AND APPARATUS FOR SUSPENSION VEHICLESUSING MULTIPLE FLUID VOLUMES” by Dennis K. Wootten et al., with AttorneyDocket No. FOXF/0022L, which is incorporated herein, in its entirety, byreference.

The U.S. patent application Ser. No. 12/407,610 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/157,541, filed onMar. 4, 2009, entitled “METHODS AND APPARATUS FOR COMBINED VARIABLEDAMPING AND VARIABLE SPRING RATE SUSPENSION” by Dennis K. Wootten etal., with Attorney Docket No. FOXF/0034L, which is incorporated herein,in its entirety, by reference.

The U.S. patent application Ser. No. 13/005,474 claims priority to andbenefit of U.S. Provisional Patent Application No. 61/294,458, filed onJan. 12, 2010, which is incorporated herein, in its entirety, byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a gas springfor use in a vehicle suspension system.

2. Description of the Related Art

Gas springs are typically utilized in suspension systems with dampers.The dampers provide a damping function as fluid is metered through apiston while the gas spring, with its compressible gas provides atypically non-linear reaction as the suspension system moves through acompression stroke. Gas volume is one aspect that enters into the designof a gas spring. A larger volume can mean a longer stoke of a piston ina gas spring before the spring becomes too “stiff” due to compression.Unfortunately a spring having a large initial gas volume also yields avery low spring force, hence too compliant, through a significantportion of a compression stroke. What is needed is a gas spring having avariable volume gas chamber.

SUMMARY OF THE INVENTION

The present invention generally relates to a vehicle suspension systemgas spring. In one embodiment, a vehicle suspension system gas springincludes a compressible main gas chamber and an additional volumecombinable with the main chamber to change a gas spring rate of thesystem. In one embodiment, a low friction piston seal is created by aflexible seal member.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features can be understoodin detail, a more particular description of the invention, brieflysummarized above, may be had by reference to embodiments, some of whichare illustrated in the appended drawings. It is to be noted, however,that the appended drawings illustrate only certain embodiments of thisinvention and are therefore not to be considered limiting of its scope,for the invention may admit to other equally effective embodiments.

FIG. 1 is a partial section view of a fork assembly showing a damper legand a gas spring leg, the gas spring leg illustrating a typical locationfor embodiments described herein.

FIG. 2A is a gas spring with a valve disposed in an upper end thereofand FIG. 2B is a view of the valve of FIG. 2A, shown in an openposition.

FIGS. 3A and 3B show another embodiment of a gas spring valve, disposedin a gas spring piston and shown in two different positions.

FIG. 4 is another embodiment of a gas spring valve.

FIG. 5 is another embodiment of a gas spring valve in a gas springpiston.

FIG. 6 is a section view of a gas spring wherein a secondary chamber iscontained in a bladder. FIG. 6 further illustrates a gas chamber fillvalve assembly.

FIGS. 7A and 7B show two positions of a gas spring with selectivelyaccessible gas volumes.

FIGS. 8A and 8B show another embodiment with selectively accessible gasvolumes.

FIG. 9 is another embodiment showing a gas spring with a gas chamberhaving a user-adjustable volume.

FIG. 10 is a section view of a gas spring wherein a main gas chamber iscompressed due to the location of a shaft assembly.

FIG. 11 is a section view of a gas spring having two gas chambers and afloating member that moves to enlarge or reduce a gas volume of the mainchamber.

FIG. 12 is a section view showing an embodiment of a combination gas andcoiled spring.

FIGS. 13A-B are section views showing an embodiment that utilizes adiaphragm in a main gas chamber.

FIG. 14 is another embodiment of the gas spring of FIGS. 13A-B.

FIG. 15 is a section view showing another embodiment.

FIG. 16 is a section view showing yet another embodiment.

DETAILED DESCRIPTION

One embodiment herein comprises a gas spring shock absorber for avehicle. In one embodiment, the vehicle is a bicycle and the gas springis disposed in a front fork of the bicycle. FIG. 1 is a section view ofa fork assembly 100 showing a damper leg 101 and a gas spring leg 105.The gas spring leg includes a gas or air chamber 112 with a gas springpiston 115 disposed on a rod 117 which extends through a bulkhead orpressure head 114. In an upper portion of an upper tube 113 and labeledas “A” is an assembly (not shown) constructed and arranged toselectively provide an additional volume to the main gas chamber 112. Inone embodiment, the additional volume comprises a secondary gas chamber.Various embodiments of the assembly will be disclosed herein. Theassembly is often located in an upper portion of the gas spring leg 105in order to permit adjustment and manipulation by a user; however otherembodiments will also be described herein.

As the gas in the primary gas spring chamber 112 is compressed operatingon only its single volume, its pressure is characteristicallyexponential and therefore increasing more rapidly through the latterhalf of the compression stroke. The force (corresponding to pressureacting over the given piston area) versus the linear travel of thepiston in the main gas chamber is not linear. While the curveapproximates linearity through about the first 50% of travel the laterportion of the stroke exhibits non-linearly increasing pressure. Atgreater travel (compression stroke) values the rate of increase of theforce (pressure) for incrementally further travel is exponential and theshock absorber is therefore increasingly much more rigid in the lastthird of its stroke. Embodiments described herein extend thesubstantially linear portion of the spring rate curve beyond thatavailable with a single gas chamber spring.

In certain embodiments there are several shock absorber parameters thatcan be varied in order to derive a preferred travel versus pressureprofile, or “spring rate” over the range of travel. Variables that maybe selectively altered include: length and diameter of a primary or maingas chamber, volume of a secondary chamber, initial pressure state ofthe primary chamber, and initial pressure state of the secondarychamber.

The initial pressure state of the primary chamber help define the shapeof the travel versus spring pressure profile for the shock absorber.Preferably the initial pressure value chosen results in a substantiallylinear spring rate for a substantial portion of the fork travel (e.g.50%+). In one embodiment of a gas spring having a selectivelycommunicable secondary chamber, the initial pressure in the secondarychamber is set to equal a pre-calculated pressure in the primary chambercorresponding to a point just before the main spring gas compressionprofile begins to become observably exponential. When the communicationvalve is opened with such secondary chamber pressure setting, there isno significant differential pressure between the primary and secondarychambers. Further, there is no significant system pressure drop when theprimary and secondary chambers are fluidly communicated. The gas springvolume is however increased by the amount of the secondary chamber andthe spring rate is correspondingly decreased. The transition from thespring rate associated with only the primary chamber to the spring rateassociated with the combined primary and secondary chambers isrelatively smooth.

In one embodiment, the initial pressure in the secondary chamber may beset at the same time as the initial pressure in the primary chamber andat the same pressure. During an initial compression of the shockabsorber the volume of the primary chamber volume is reduced and thepressure in the primary chamber rises until a communication valvebetween the primary and a secondary chamber is opened. Because thesecondary chamber pressure is still at its initial pressure setting,corresponding to the primary chamber initial setting, fluid flows fromthe now elevated pressure primary chamber, through the communicationvalve into the secondary chamber when the communication valve is opened.The pressure in the now combined primary and secondary chambersequalizes at a pressure value between the pre-communication primarychamber pressure and the initial secondary chamber pressure(equalization pressure is dependent on the volume ratio between theprimary and secondary chambers). Following that combination andequalization the slope of the spring rate for the combined chambers ismore gradual. During subsequent compression cycles of the shockabsorber, the secondary chamber retains the “at communication”compression pressure of the primary chamber as a set point and nofurther equalization occurs upon opening the communication valve.

In one embodiment, a pressure regulator is positioned between theprimary and secondary chambers and maintains a predetermineddifferential pressure between the two chambers when the communicationvalve is closed.

Variable volume gas springs are disclosed in US Patent ApplicationPublication Nos. 2009/0236807 A1 (application Ser. No. 12/407,610);2003/0234144 A1 (application Ser. No. 10/237,333); 2008/0116622 A1(application Ser. No. 11/560,403); and 2008/0296814 A1 (application Ser.No. 12/176,160), each of which is incorporated herein, in its entirety,by reference. As used herein, “air” and “gas” may be used to designateany suitable gaseous phase fluid. “Up”, “down”, “Upward” and “downward”are used herein to designate relatively opposite directions, usually ofmovement.

Referring to FIG. 2A, a sectional view of one embodiment of portion ‘A’of the gas sprung vehicle shock absorber (or gas spring fork leg) ofFIG. 1 is shown. Illustrated is a main gas chamber 112 with a gas piston115 shown in a retracted position. A valve 200 is located opposite thepiston 115 and includes a movable valve piston 205 with an upper area202 defined by an upper O-ring seal 212 and a lower area 207 defined bylower O-ring seal 214. A secondary gas chamber 220 is formed annularlyaround the valve piston 205 and is bounded by another set of O-rings213, 217. Secondary gas chamber 220 is for selective use in order toadditively enlarge the size of the main gas chamber 112 as describedbelow. Valve 200 is retained in cylindrical tube 113 with threadsbetween the valve body 203 and a threaded cap 218, an outer surface ofwhich is threaded into an upper end of the tube 113.

In one embodiment, the upper piston area 202 is larger than the lowerarea 207 and is acted upon by a valve gas chamber 210 formed above theupper area. Due to the differences between piston surface areas, thevalve piston 205 can be in a balanced state when main gas chamber 112pressure is higher than valve gas chamber 210 pressure. Additionally, anisolated area 215 is defined between upper O-ring 212 and anintermediate O-ring 211, sealing the valve piston 205 within the valvebody 203. Area 215 will typically include gas at atmospheric pressure(versus the often higher pressures of chambers 112, 210 and 220) andwill resist any movement of valve piston 205 that increases the volumeof area 215. A bleed valve or port 216 is installed adjacent isolatedarea 215 to facilitate assembly of the valve 200 by allowing evacuationof gas from chamber 215 during assembly.

When pressure in the main gas chamber 112 becomes high enough, due tocompression of the fork and hence the main gas chamber of the gasspring, the net force on the lower area 207 of the valve piston 205becomes greater than the net force on the upper area 202 of the piston205 (which equals the valve gas chamber pre-charge pressure multipliedtimes the upper area), and any resistance contributed by the potentialaxial expansion of isolated area 215. At that point, the valve piston205 is moved upwardly, thereby exposing secondary gas chamber 220 to themain gas chamber 112. FIG. 2B illustrates the valve in the open positionwhich will take place at some point during a compression stroke of maingas piston 115 (not shown in 2B). As shown, a lower end 222 of the valvepiston 205 is moved off a seat 223 formed in the valve body and a fluidpath 225 is formed between the chambers 112, 220. Such fluidcommunication results in an increased fork leg air spring (or gas)volume and therefore a reduced, or more linear, effective spring rate.

Initially the valve gas chamber 210 is configured with a gas pressure asdesired to permit opening of the valve 200 at a predetermined point inthe compression of the main gas chamber 112. While the initial charge ofthe secondary gas chamber 220 can be preset, it is not necessary. Oncethe valve piston 205 has cycled open during compression, the pressure ofthe main gas chamber 112 at the predetermined compression point will beintroduced into the secondary gas chamber 220. During extension of thefork (e.g. rebound and decompression) the valve piston 205 will closewhen the pressure of the main chamber 112 becomes insufficient tocontinue to overcome the net force on the upper area 202 (accountingalso for the force due to chamber 215) of the valve piston 205. Closureof the valve piston 205 will trap the pressure of the main chamber 112in the secondary chamber 220 at a value of pressure that existed at thetime of closure. Subsequent cycles will operate consistently because thepressure in the main and secondary chambers 112, 220 will besubstantially the same at the point of subsequent valve openings.

FIGS. 3A and 3B show another arrangement that is operationally similarto the arrangement of FIGS. 2A, B but where the secondary chamber andcommunication valve are included with the compression piston versus thetop cap area. The FIGS. 3A, 3B show a gas spring with a threaded cap 318in an upper end of a tube 113 and a piston/rod assembly in a lower endof the tube as it would appear prior to a compression stroke. In theembodiment of FIGS. 3A, B the valve arrangement is configured as part ofthe gas spring piston 115 (as opposed to the piston of FIG. 1, forexample) and the valve assembly moves with the piston 115 into the gaschamber 112 during a compression stroke of the gas spring. As shown inFIG. 3A (and referencing FIG. 1 for analogous “upper” and “lower” areas)the main chamber 112 is above the valve 300. The valve piston 305 isannular and includes a larger “upper” annular area 302 on its lower endand a smaller “lower” annular area 307 on its upper end. In theembodiment shown, area 307 is accessed through some number of ports 308formed in a head piece 303 of the gas piston 115.

Operationally, the valve piston 305 and its upper and lower areas 302,307 communicate a secondary gas chamber 320 with the main gas chamber112 at a predetermined point in the compression of the main gas chamberand based on the preset gas pressure of a valve gas chamber 310. FIG. 3Bshows the device in an “open” position with end 322 of the valve piston305 moved off a seat 323, thereby permitting fluid communication (shownby arrow 325) between the main 112 and secondary 320 gas chambers. Aswith the valve of FIGS. 2A, B, the valve operates to increase the gasvolume of the spring when pressure acting upon piston area 307 overcomespressure in piston area 302 plus any resistance brought about by theexpansion of an isolated area 315.

FIGS. 4 and 5 show embodiments of the valve whereby only two pressurizedchambers are used with the addition of a check valve added therebetween.In FIG. 4 for instance, pressurized gas in the main chamber 112 actsupon a first piston surface 407 of a valve piston 405 via apertures 408formed in the body 403 of the valve 400. Acting opposite the firstpiston surface 407 is another, larger piston surface 402 adjacent asecondary gas chamber 420 (this embodiment does not include a valve gaschamber). A bleed valve 416 is used to facilitate assembly of the valve400. At a predetermined pressure in a compression stroke of the gasspring piston 115, the valve piston 405 moves against the pressure ofthe secondary chamber 420 (and against any resistance brought about byan enlargement of an isolated area 415) and fluid communication isinitiated between the two chambers 112, 420. When the valve returns to a“closed” position (shown in FIG. 4) a check valve 430 disposed betweenthe two chambers and preset to open above a certain pressure (asdetermined by compression of spring 432) in the secondary chamber 420,permits communication between the chambers, thereby ensuring that thesecondary chamber 420 is not left with an unsuitably high pressure thatmight prevent the valve from operating correctly in subsequent cycles.In operation, the check valve opens during a rebound stroke of thepiston 115 as pressure in the main gas chamber is reduced. Check valveshaving spring biased cracking pressures are well known in the art andinclude an adjustable spring member 432 and a spherical closing member434 that is locatable on a seat 436 in order to seal or permit fluidfrom passing through an orifice 438 of valve piston 405 in which thecheck valve 430 is located.

FIG. 5 is another embodiment of a valve like the one in FIG. 4 but inthis embodiment, the valve 500 is disposed in the main gas spring piston115. The valve includes a movable valve piston 505 having a first pistonsurface 507 acted upon by pressure in the main gas chamber 112 and anopposing, larger piston surface 502 acted upon by pressure in asecondary chamber 520. The piston 505 is constructed and arranged toremain in a closed position shown in FIG. 5 until pressure in the mainchamber 112 acts upon piston surface 507 (via apertures 508) with enoughforce to move the piston 505 against the opposing force of secondary gaschamber 520 and any resistance of an isolated area 515 formed betweenthe valve piston 505 and the valve body 503. It is noteworthy that whilethe isolated area often provides resistance to opening by virtue ofhaving a set pressure lower than other system operating pressures, insome embodiments a higher than system pressure is installed in theisolated area thereby allowing it to aid in opening of the valve.Referring again to the embodiment of FIG. 5, once the valve piston movesoff a seat 523 in the valve body, fluid communication is permittedbetween the gas chambers 112, 520, typically towards the end of acompression stroke of the gas spring piston 115. Thereafter, during arebound stroke, check valve 530 permits higher pressure gas in thesecondary chamber 520 to return to substantially equalize (consistentwith the spring cracking pressure) with the main chamber 112, therebypreparing the valve 500 to operate in the next cycle. In the embodimentof FIG. 5, the secondary gas chamber 520 communicates with the checkvalve 530 via a fluid path 540 extending from the chamber through a bore541 formed in the valve 500.

FIG. 6 shows, in section, another embodiment of portion ‘A’ of the gassprung vehicle shock absorber (or gas spring fork leg) of FIG. 1. In oneembodiment, a bladder-type member 602 forms a secondary chamber 601which is separated from a main gas chamber 112 by the bladder 602. Aninterior of the bladder 602 is initially pressurized to a pressure valuehigher than the fully extended main gas chamber 112 pressure. When thesuspension is extended (and chamber 112 at correspondingly low pressure)the pressurized bladder is constrained from over expansion as previouslydescribed. Communication between main chamber 112 and bladder chamber601 is provided via an annular fluid path (or circumferentially spacedapertures) 617 between the bladder ring 605 and an inner wall of tube113. The gas chamber compresses during a compression stroke of the fork(or shock) and the pressure therein rises. When the gas chamber 112pressure becomes equal to the interior bladder pressure, gas in thebladder 602 begins to compress along with the gas in chamber 112 as thecompression stroke of the fork spring continues. FIG. 6 shows thebladder 602 in such a partially compressed condition. The addition ofthe compressing bladder 602 effectively increases the compressing gasvolume beginning or “triggered” at a certain suspension compressioncorresponding to the preselected interior bladder pressure, therebyreducing the slope of the effective spring rate curve for the totalspring. When the fork spring is extended during rebound the bladder 602will expand until it fills the chamber in which it is housed. At thatpoint the bladder will remain at its pre-charged condition while the gaschamber 112 pressure continues to decrease during continued forkextension.

Looking at FIG. 6 in more detail, the bladder 602 has walls formed of aflexible material having enough strength to withstand the pressures andmovements expected of it in use. The bladder is located above the mainchamber 112 and piston (as shown for example in FIG. 1). An outer wallof the bladder is housed in and retained by the tube wall 113 and aninside wall of the bladder is retained (from over-collapse) by an outersurface of a shaft 607 extending through the upper portion of the forkleg 105 and used to fill the chambers 112, 601 as will be described. Ata lower end, the bladder is retained and effectively sealed betweenbladder ring 605 which supports its lower end and prevents it from“extruding” into the gas chamber 112 therebelow and an upper bladderring 610, with both rings supported on shaft 607 by retention rings 614.

Another similar pinch-type connection is formed at an upper end of thebladder 602 to seal its perimeter. As shown in the Figure, an upper edgeof the bladder is retained in an annular space 615 formed in an outerdiameter of fork cap 612. An upper portion, and hence the interior, ofthe bladder is open to another annular area 611 formed in an interior ofthe fork cap 612. The separation of the chamber 601 from the mainchamber 112 by use of a bladder 602 is advantageous in that no frictiondue to moving seals (e.g. of floating pistons) is introduced into thesystem and therefore the transition from compression of the gas chamber112 to compression of the combined gas chamber 112 and gas-filledbladder 602 is very smooth. Notably, gas in the main chamber 112 neednot be the same “gas” or have the same characteristics as gas in thebladder.

In the embodiment of FIG. 6, a multi tank gas fill valve 620 is shownwithin the top cap 612. In one embodiment, the gas fill valve includesan axially movable filler body 621, having a bore 622 formedsubstantially along its length but ending as a blind hole in a lowerportion thereof. An upper set of radial apertures 623 straddled byO-rings 625 (or other seals) above and below, intersect the bore 622. Alower set of radial apertures 627, straddled by O-rings 625 (or otherseals) above and below, also intersect the bore 622 of valve body 621.In its axial upper position (as shown in FIG. 6), gas pressure may beintroduced at an upper end of the fork through bore 622 of the fillerbody 621 (which in one embodiment comprises a Schrader type fill valvedepicted as a threaded body extending upwardly from the center of cap612) where it flows and subsequently exits through unsealed apertures627 (utilizing a space between the lower O-ring 625 and an upset 629),entering a bore 630 (through the shaft 607) and exiting into the gaschamber 112, thereby increasing pressure in, and “filling,” the main gaschamber.

In a second position (not shown), the filler body 621 is moved downward,thereby closing a gap 632 formed between an outwardly extending lip ofthe filler body and a shoulder 633 of cap 612. In that downwardlyshifted position, apertures 623 will be adjacent an apertures 634 formedthrough a wall of the valve body 621 (with O-rings 625 above and belowsealingly straddling aperture 634) and apertures 627 will be located inupset 629 with O-rings 625 above and below sealingly straddling upset629 (thereby sealing apertures 627 closed against the inner surface ofthe shaft 607). As such, gas may be introduced into bore 622 where itwill flow until it exits though apertures 623 and aligned apertures 634and into secondary chamber 601, thereby increasing the interior pressurein the bladder 602. As such the valve 620 is essentially a two-position“push/pull” valve that may be used to independently fill two isolatedregions of a gas spring.

FIGS. 7, 8 and 9 each show, in section, an embodiment of portion ‘A’ ofthe gas sprung vehicle shock absorber (or gas spring fork leg) ofFIG. 1. FIGS. 7 and 8 show embodiments of a multiple air volume gasspring that each use some form of sequential port straddling where eachport optionally straddled communicates with a gas volume. FIG. 9 showsan embodiment that permits a main gas chamber to be enlarged to any sizewithin the range of an adjustment feature.

In the embodiment of FIG. 7A, B, for example, an upper portion of a forktube includes multiple additional gas chambers that can be selectivelyutilized based upon an adjustment made by a user of the sock absorber.Visible in the Figure is upper tube 113 of a fork, the inside wall ofwhich serves as an outer wall for three additional gas volumes 701, 710,715. The volumes are selectively put into communication with a main gaschamber 112 based upon the axial position of a chamber sealing screw 720which includes a spaced pair of straddling seals 742, 743 at a lower endthereof and is axially translatable up and downwards along a multichamber shaft 725. In the embodiment of FIG. 7A, a hex drive coupler 730extends downward from an upper end of the fork. The coupler has a crosssection male hex shape formed on its outer surface that mates with across section female hex shaped surface formed on the interior of thechamber sealing screw 720. The mating hex shapes ensure the two parts730, 720 are rotationally but not axially fixed together. Specifically,the arrangement permits the hex drive coupler 730 to be rotated, therebycausing the chamber sealing screw 720 to move up or down due to athreads 732 on an outer surface of the screw 720 and mating threads 733the interior of the multi chamber shaft 725. At an upper end, the hexdrive coupler 730 is attached and rotatable by a compression ratio knob735 located at an upper end of the fork. In the embodiment shown, therotation of the knob is indexed by a ball and detent arrangement 740consisting of a spring-loaded ball that seats itself in one of anynumber of detents that help determine and limit rotational movement ofthe knob 735 and with it, axial movement of the sealing screw 720. Anadditional top cap 736 houses a path to pressurize the main chamber 112via a hollow shaft 737 and typically includes a Schrader valve (depictedas a threaded portion under and within cap 736).

In one embodiment, the chamber sealing screw 720 is moved axially toposition upper 742 and lower 743 seals of the screw in sealingstraddling arrangement over selected entry ports 745, 746, 747 thatcorrespond to additional spring air volumes 701, 710, 715. Opening ofthe ports adds their corresponding air volume to the main spring, hencereducing the total spring rate. Conversely, subtracting the portsremoves the air volume from the total thereby increasing the gas springrate of the fork. In FIG. 7A, the gas spring is shown with only the maingas chamber 112 utilized. All of the additional volumes 701, 710, 715are isolated from the gas chamber 112 due to the position of the lowerseal 743 of the chamber sealing screw 720 that is preventingcommunication with volume 701.

FIG. 7B shows the embodiment of FIG. 7A after the knob 735 (not shown)has been manipulated, thereby rotating the hex drive coupler 730 andcausing the chamber sealing screw 720 and seal member 743 to moveaxially upwards to expose, and thereby add, two volumes 701, 710 to themain chamber 112. The path of air into each volume is illustrated byarrows 750.

FIGS. 8A and 8B show another embodiment of a valve having auser-selectable means of utilizing additional gas spring volumes inorder to change spring rate. In the embodiment shown in FIG. 8A, amulti-chamber shaft 825 includes two additional volumes 801, 810accessible via apertures 845, 846, while an axially adjustable traveladjuster 820 (operationally analogous to and operational as the chambersealing screw 720 of FIG. 7) includes sealing O-rings having differentdiameters. The varying diameters of O-rings 843, 844 permit operation ofthe valve with less axial movement, as compared to the chamber sealingscrew 720, between positions. In FIG. 8A both additional volumes 801,810 are in fluid communication with main chamber 112 via fluid paths826, 827, and in FIG. 8B only a single volume 801 is being utilized dueto the contact of O-ring seal 844 with its corresponding surface of themulti chamber shaft 825. Referring to the FIGS. 8A, B, when seal 843becomes sealingly engaged with an interior of the chamber shaft 825, allof the optionally additional volumes are isolated from the main chamber112. Note that indexer (as shown in FIG. 7) may be calibrated to engagedetent at appropriate axial relationship seal increments as required.Adjustment of the travel adjuster 820 is typically accomplished with amechanism similar to that described in relation to FIGS. 7A, B.

In each of FIGS. 7 and 8 the spring rate adjustment is made by usermanipulation of an adjustable member. Note that these manuallyadjustable embodiments may be used in conjunction with “automatic”embodiments disclosed herein (e.g. FIGS. 2-6; 10-12) such that the totalspring exhibits a combination of automated (or preset) rate and manuallyselectable rate adjustments. Further, while one or two additional gaschambers may be shown and described it is understood that in manyembodiments more gas chambers may be added in keeping with principlesdisclosed herein.

In another embodiment as shown in FIG. 9, the total volume of the maingas chamber 112 is infinitely variable (within mechanical limits). Auser may rotate a compression ratio shaft 901 (via an adjustment knob905) thereby axially moving (upward for increased spring volume ordownward for decreased spring volume) a compression ratio piston 910.Movement is accomplished with mating threads 916, 917 formed on the twomating portions 901, 910. As in the embodiment of FIG. 7, the knob 905is provided with a ball and detent mechanism 940. As the ratio piston910 moves upwards, additional portions of a normally unused and isolatedvolume 915 are utilized as part of the main chamber 112. In theembodiment of FIG. 9, the ratio piston 910 is keyed (with a key 920 andslot 925) to a wall of the fork tube 113 in order to ensure it remainsrotationally located, so that the threads 916, 917 will turn relatively,as the compression ratio shaft 901 moves along it axially.

In one embodiment, as shown in FIG. 10, the piston rod 1010 (see FIG. 1)is hollow, referred to as lower air shaft assembly, and includes asecondary air volume. However, in FIG. 10, the lower leg portion of thefork is not shown in order to more clearly illustrate a lower air shaftassembly 1010 which is effectively fixed at a lower end 1012 to thefront wheel (not shown) of the vehicle and moves in and out of the uppertube portion 1014 with the lower leg portion as a main gas chamber 112is compressed in operation. In one embodiment, the compression of themain gas chamber is achieved by introduction of the volume of the lowerair shaft assembly 1010 into the volume of the main chamber 112 during acompression stroke. As such, the “piston” portion 1016 of the lower airshaft assembly need not sealingly engage the inner surface of the uppertube 1014, thereby eliminating a dynamic seal. Rather the lower assembly1010 is sealed at a lower end of the tube 1014 by a sealhead 1020 havingO-ring seals 1021, 1022 on an inner and outer surface thereof. Theembodiment of FIG. 10 also includes a mechanical “negative” spring 1015that is compressed between piston 1016 and sealhead 1020 of the main gaschamber 112. Negative springs urge a gas spring like the one showntowards compression and are useful in smoothing the initial movement ofan air spring. As illustrated by the Figure, the embodiment shown uses avolume of a rod, rather than a sealed piston to compress gas in a mainchamber (although either may be used as the compression mechanism). Inthis manner, an annular area between the rod of the shaft assembly 1010and an inner surface of upper tube 1014 buffers the compression of thegas in the main gas chamber 112.

FIG. 11 shows an embodiment of a spring leg (FIG. 1). Like the otherembodiments, the fork leg 1114 includes a filling means at an upper end1113 thereof typically including a Schrader valve and a fluid path 1124extending to a main gas chamber 112. Like the embodiment of FIG. 10, anouter, lower tube is not shown so that a lower portion of the assemblycan be illustrated more clearly. In one embodiment, a lower air shaftassembly 1110 includes an internal floating piston 1115 disposed at afirst end thereof and in fluid communication with a main gas chamber 112via an aperture 1117 formed in a main air piston 1118. As with theembodiment of FIG. 10, the spring leg is equipped with a negative spring1116 to initiate compression. In one embodiment, the lower air shaft1110 includes an gas chamber 1119 which is initially pressurized to avalue higher than that of the main chamber 112. As the main chamber 112is compressed during a compression stroke of the suspension, thepressure therein increases until it equals the preset pressure insidethe air cylinder 1119. Subsequently, as the pressure in the main chamberincrementally rises beyond that of the lower cylinder, the floatingpiston 1115 begins to move in the direction of a lower end 1112 of thelower air shaft 1110, thereby transferring incrementally increasedpressure to the air cylinder 1119 and correspondingly including itsvolume in a total air volume of the fork spring. As with otherembodiments, the piston surfaces 1120, 1122 on each side of the floatingpiston 1115 can be designed, along with the beginning pressures in eachchamber 112, 1119, to effectively “tune” the gas spring to desiredcharacteristics.

In one embodiment shown in FIG. 12, a main chamber 112 includes ahelically wound (or other) mechanical spring 1205. The helical springcan either act alone in the chamber 112 or can augment pressurized gasin the chamber. For example, in one embodiment, the chamber 112 alsoincludes compressed air at a predetermined pressure whereby, in acompression stroke, both the gas and helical spring 1205 work togetherto determine an overall spring rate. In one embodiment, the function ofthe main spring is performed solely by the mechanical spring. The mainchamber 112 is typically fillable through a fill valve located at alower end of the fork (not shown). In an upper area of the tube 113 is asecondary gas chamber 1210 constructed and arranged to be compressed asa sealed main gas piston 1215 moves into the chamber 1210 during acompression stroke of the main spring. A fill means 1220, typicallyincluding a Schrader valve provides a path 1225 with apertures 1230 forpressurizing the secondary chamber 1210. In one embodiment, a shaft 1245extends along the center of the tube 113 and terminates in a top outring 1240 to retain the piston 1215 in its initial position prior tocompression. An integrated spring guide 1250 ensures the helical spring1205 stays centered in the tube 113.

In one embodiment, the main spring and gas chamber pressure(s) arearranged and set whereby during a first half of compression stroke, only(or substantially) the helical spring 1205 will determine the springrate. Thereafter, in a later part of the stroke, the gas portion(s) willdetermine the spring rate after the spring 1205 compresses to a pointwhere the air piston 1215 begins to move significantly upwardly, therebycompressing the gas in the secondary air cylinder 1210 and affecting thespring rate of the total compound spring.

FIGS. 13A-B illustrate an embodiment of a “rolling diaphragm” or bladderfor isolating (sealing) a main gas chamber of a suspension air spring.The gas spring in FIG. 13A is shown in a fully extended position and inFIG. 13B is shown in a compressed state. Like the bladder embodiment ofFIG. 6, this type of isolated volume is advantageous because it requiresno dynamic seals and as such is relatively frictionless and responsiveand will operate very smoothly.

As shown in the Figures, an upper fork tube 113 forms a main gas chamber112 by supporting a flexible bladder or diaphragm 1305 housed therein.The diaphragm is under pressure, allowing it to extend downwardly in thetube when the air spring is in a retracted position as in FIG. 13A. Anupper end of the diaphragm 1305 is retained in an annular area 1310formed in a top cap 1315. At a lower end, the diaphragm 1305 is abuttedby and, in the embodiment shown, attached to an upper end of a plungeror piston 1320 where it is housed in an annular area 1325 formed arounda piston cover 1335 and retained by a ring 1330. The piston is attachedvia a piston rod, to a lower leg (not shown but visible in FIG. 1). Avalve in the top cap 1315 provides a means of filling the diaphragm 1305to a pre-compression pressure.

As the suspension compresses (during a compression stroke) and the uppertube 113 moves into the lower leg, the piston 1320 begins to impingeupon and deform (essentially “turn inside out”) an end of the diaphragm1305. As is shown in FIG. 13B, the diaphragm essentially turns in onitself and the volume interior of the diaphragm (i.e. the main gaschamber) is decreased by the volume of the impinging piston. The pistoncover 1335 comprises in whole or in part a flexible material such anelastomer that will make it more robust and reduce side loading of thediaphragm 1305 by the piston 1320. The cover also serves to enlarge adiameter of the piston and make its volume more effective in compressingthe diaphragm. The cover 1335 also may include centering ribs (notshown) which are rigid enough to guide the piston along the innersurface of the upper tube rather than the side surfaces of the rolleddiaphragm 1305.

FIG. 14 is another embodiment of the gas spring of FIGS. 13A-B. Like thedevice of FIG. 13, the spring includes a main chamber 112 with adiaphragm 1305 disposed therein and is illustrated in itspre-compression position. Unlike the embodiment of FIG. 13, thediaphragm in FIG. 14 is not mechanically attached to the piston/pistoncover 1320, 1335 at a lower end. Rather, the diaphragm is free to befurther deformed simply by the movement of the piston in the compressionstroke.

In one embodiment, as shown in FIG. 15, a gas spring assembly includes amain gas chamber 1505 as well as a secondary chamber 1510 housed in alower air shaft 1515. The lower air shaft is equipped with a piston 1520at one end for compressing gas in the main chamber 1505 as the lower airshaft 1515 extends into the upper tube 1525 during a compression stroke.Disposed in the piston 1520 in a slidable relationship is a spring shaft1530. The shaft is constructed and arranged to add and subtract volumefrom the two chambers 1505, 1510 as the gas spring operates. Forexample, in one embodiment, in a retracted state, the secondary gaschamber 1510 is at higher pressure than the main chamber 1505 and istherefore urging the slidable spring shaft 1530 into the main chamber1505 (against a coil spring 1535 that is disposed between the piston1520 and a stop 1521). As the gas spring operates in a compressionstroke, the spring shaft 1530 and its volume move into the main chamberand displace gas therein, thereby increasing the gas pressure in themain chamber 1505 until the main chamber is at a pressure equal to thatof the secondary chamber 1510. At that point (due to force of the spring1535) the spring shaft 1530 moves back into the secondary chamber 1510,thereby permitting an enlargement of the main chamber volume by anamount equal to the volume of the spring shaft 1530 that has moved outof the main chamber 1505. In this manner, the volume of the main chambercan be increased or decreased in an “automatic” fashion as the gasspring operates. Because each chamber 105, 1510 can be preset withdiffering gas pressures, the spring can be tuned to operate according tothe needs of a user.

In one embodiment, as shown in FIG. 16 a gas spring includes an uppertube 1605 having a lower end 1606 partially sealed by a piston 1610having an O-ring 1615 or other suitable dynamic seal around an exteriorthereof. During compression of the fork leg, the piston moves downwardinto a lower leg 1620, thereby compressing the main gas chamber 1625 andproviding spring force resisting compression. The main chamber 1625 hasa user selected and suitable initial pressure value. In one embodiment,a mechanical spring 1630 is connected between a lower end of the piston1610 and a lower end 1621 of the lower leg 1620 such that the spring1630 is in tension when the gas spring is extended. The mechanicalspring 1630 thereby urges the upper tube 1605 downward, or the lower leg1620 upward relatively (as it is only relative movement that is urged)from its fully extended position, thereby performing as a “negative”spring as described with reference to previous embodiments.

In the embodiment shown, the piston 1610 includes an aperture 1612therethrough whereby gas is communicated between the main gas chamber1625 and a secondary gas chamber 1608. The aperture permits gas to acton a floating piston 1640 disposed in the upper tube in a manner wherebythe floating piston will move further into and partially out of thesecondary gas chamber 1608, thereby permitting the main gas chamber 1625to be enlarged or reduced as the gas spring operates. In one embodiment,secondary gas chamber 1608 is initially charged to a higher pressurethan main gas chamber 1625, whereby both pistons 1610, 1640 initiallyoperate as one during an initial compression stroke. Thereafter, as gaspressure in the main gas chamber 1625 increases to a level of both thepressure of the secondary gas chamber 1608, floating piston 1640 willmove upwards into secondary gas chamber 1608. In one embodiment, (notshown), an automatic, pressure-actuated valve like the one shown in 2A,B is installed at an upper end of the upper tube 1605. As described inreference to FIGS. 2A, B, the valve is constructed and arranged to“open” when pressure in the secondary chamber 1608 rises to apredetermined level, thereby providing another chamber and enlarging thesize of the secondary gas chamber 1608 and/or the size of the main gaschamber 1625.

In one embodiment, a manually selectable secondary and/or tertiary (orfurther) gas chamber (e.g. FIGS. 7-9) are positioned at an upper ‘A’portion of the fork leg (FIG. 1) to augment the secondary gas chamberwithin the upper tube (or to act as a secondary, etc. in the event thatthe floating piston is absent and the upper tube chamber and “main”chamber are merely communicated and experience a decreasing total volumeupon compression).

While the embodiments have been described separately, they can becombined and need not be located in a particular fork leg. For example,considering the fork of FIG. 1, a fluid flow could traverse (e.g. eitherinterior to or attached to) a fork crown between the two fork legs,thereby establishing a fluid communication path between the legs. Assuch, additional damping chambers may be located in the gas spring leg(or the gas spring pressure may be used to enhance dampening) oradditional gas volumes may be located in the dampening leg andcommunicated (additively as described herein) to the gas volumes of thetotal gas spring.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the scope thereof, and the scope thereof is determined bythe claims that follow.

1. A vehicle suspension system gas spring, comprising: a compressiblemain gas chamber; and an additional volume combinable with the mainchamber to change a gas spring rate of the system.